SIOUX FALLS, S.D. — The FBI says a black civil rights activist was killed during the 1973 occupation of Wounded Knee, and it suspects militant members of the American Indian Movement are responsible, according to recently released documents.

The hundreds of pages of reports provided to Buffalo, N.Y., attorney Michael Kuzma and shared with The Associated Press Wednesday shed new light on the 40-year-old case of Ray Robinson, an activist and follower of Martin Luther King Jr. But the documents fall short of pinpointing where Robinson was buried and do little to fulfill his family’s wish to have the remains brought home to Detroit.

Desiree Marks, who’s held out hope for 40 years that she’d see her father again, said she was crushed by the FBI’s confirmation of his death.

“I’ve always thought that might not be the case. He may come home. He may be alive. He may, he may, he may,” Marks told The Associated Press on Wednesday. “And yesterday, when I was reading the documents it was very difficult. It made it real final.”

AIM co-founder Clyde Bellecourt said Wednesday that he was only in Wounded Knee for 51 days and knew nothing of Robinson.

“I don’t know who he is,” Bellecourt said. “I never met him. I don’t know what he looks like.”

Robinson, a father of three from Bogue Chitto, Ala., traveled to South Dakota's Pine Ridge Indian Reservation in April 1973 to stand alongside Native Americans in their fight against social injustice. The 71-day standoff between AIM members and federal agents at Wounded Knee left at least two tribal members dead and a federal agent seriously wounded. The Pine Ridge Indian Reservation occupation is credited with raising awareness about Native American struggles.

The documents were released in response to Kuzma’s June lawsuit against the U.S. Justice Department to help Robinson's widow, Cheryl Buswell-Robinson, and their children get some closure.

Buswell-Robinson, of Detroit, said her husband’s nonviolent approach conflicted with the violent situation at Wounded Knee and that it’s possible AIM members suspected he was a federal informant. The personable, 6-foot-2 black man with a deep baritone voice would have stood out on a Midwest American Indian reservation, she said.

Robinson’s family just wants to bring his remains home for a proper burial.

“I’d just like to have my dad. I’d like to have a place where I can sit down and talk to him and know he’s there,” said Marks, who also lives in Detroit.

The Robinson case, which has been opened, closed and reopened over the years, was most recently closed again in July, said Greg Boosalis, an FBI spokesman in Minneapolis.

“If new information comes forward that is substantial, we will reopen it,” Boosalis said.

According to the FBI documents, an unidentified cooperating witness told agents that “Robinson had been tortured and murdered within the AIM occupation perimeter, and then his remains were buried ‘in the hills.’”

Any search or excavation attempts would likely be complicated by the reservation’s sovereign status. Buswell-Robinson and her two daughters traveled to Wounded Knee in 2004 to walk areas that Robinson likely walked, but they came back without answers.

Another witness told agents that Robinson was in Wounded Knee for about a week and had difficulty adjusting to the lack of food, the chaos of the scene and the unilateral AIM command. That witness said Robinson immediately wanted to open discussion in the bunker about AIM’s strategies but no one listened or took him seriously.

The witness said Robinson got into a heated exchange with another person and was taken to a house by a security team. When Robinson grabbed a knife from a table, he was circled by AIM security guards, according to the witness. A shot rang out, and Robinson’s eyes “rolled up as he went down.”

Buswell-Robinson, 69, questions that account and believes Robinson was in the Wounded Knee occupation area for hours, not weeks. She said the most likely account of her husband’s death is one passed on to her by Barbara Deming, a writer and political activist who was asked by Buswell-Robinson in the mid-1970s to look into the killing. She relayed the story to Buswell-Robinson in letters years after the disappearance.

According to Deming’s account, Robinson was eating oatmeal one day but hadn’t yet checked in with an AIM leader. He was ordered to report to the leader immediately but said the check-in had to wait until he was finished eating. He was then shot, according to the story.

“Ray did not respond well to that authoritative direction,” Buswell-Robinson said.

The wounded Robinson was taken to a clinic, but the FBI hasn’t pinned down what happened next.

For decades, AIM leaders have denied knowledge of Robinson’s death. One witness told agents that AIM leader Vernon Bellecourt, who died in 2007, knew Robinson had been killed and “made a statement to the effect that AIM had ‘really managed to keep a tight lid on that one' over the years.’”

AIM leader Dennis Banks did not return a message left by The Associated Press on Wednesday.

Clyde Bellecourt questioned why the FBI wasn’t spending its time investigating the many unsolved Native American deaths during Wounded Knee.